The present invention relates to a rotor core or generator manufactured according to a manufacturing method of rotor core that comprises a generator rotor or a manufacturing method of generator, particularly to an AC generator for vehicle.
An AC generator consists of a rotor comprising a rotor core, on which an exciting coil is wound, to be fixed around a rotary shaft facing each other and a stator comprising an annular stator core, on which a stator coil is wound, to be mounted facing the rotor with a clearance therebetween.
The generator as above described is designed to generate dielectric electromotive power in the stator coil but, when current is generated in the stator coil, magnetic flux is generated by the armature reaction.
Due to the interaction between the magnetic flux caused by the armature reaction of the stator coil and that of the exciting coil of the rotor, a magnetic vibro-motive force is generated between the stator and rotor. It is well known that this force is transmitted to the structure, including stator core and bracket, and the vibration of the structure is then emitted as magnetic noise.
In order to attenuate the magnetic noise, it is well known that, as disclosed in the Japanese Patent Publication No. Hei 06-48897 (1994), for example, a tapered surface is provided on the rear end in the rotational direction on the outer perimetric surface of a magnetic pole claw of the rotor core protruding in the same coaxial direction.
Recently, for achieving higher output, permanent magnets have been installed between the magnetic pole claws of the rotor core mounted around a shaft facing each other. In order to hold the permanent magnet, it is well known that, as disclosed Japanese Application Patent Laid-Open Publication No. Hei 09-98556 (1997), a permanent-magnet fastener is provided on the inner perimetric end of the magnetic pole claw.